1. Technical Field
The present invention relates to image reconstruction, and more particularly, to a method for reconstruction from rotational projection sequences.
2. Discussion of Related Art
According to the American Heart Association, Cardiovascular Disease (CVD) is responsible for more than one third (36.3%) of total deaths in the United States in 2004. The gold standard for diagnosis of coronary artery disease, a commonly known CVD, is rotational x-ray angiography. Rotational x-ray angiography uses a contrast agent injected in the coronary arteries and a c-arm gantry rotating around the patient to provide a set of projection images from different angles. This x-ray examination of the coronary arterial tree is used to diagnose and locate defects, blockages and/or stenoses in the blood vessels. Since these measurements are based on a two-dimensional (2D) projection on a 2D plane of the coronary arteries, they represent a simplification of the real three-dimensional (3D) structures. Hence, visual interpretation based directly on 2D images suffers from inaccurate depth information and from superimposition effects.
Several approaches have been proposed to obtain a full volume 3D reconstruction from projection images. Filtered back projection algorithms from computerized tomography (CT) have been introduced to generate a 3D model based on the Feldkamp-Davis-Kress geometric settings for imaging of static objects. However, direct tomographic reconstruction of coronary arteries from a rotational X-ray sequence, in a CT-like manner, suffers from cardiac motion and respiratory motion shown in the rotational X-ray images, which can result in significant reconstruction artifacts. Dynamic 3D reconstruction of coronary arteries from biplane angiography has been investigated using two synchronized projections of the coronary tree and a manual identification of vessel's bifurcation point to refine the calibration of the camera system. But, in many cases, using only two projections is not sufficient to obtain automatically a precise reconstruction of the complicated coronary trees. The number of projections used for reconstruction can be increased by selecting the ones that correspond to the same cardiac phase from a rotational X-ray sequence. However, this results in discarding a large number of acquired images, or a prolonged acquisition time when a given number of views are needed for a satisfactory reconstruction.
Therefore a need exists for a method for reconstruction from rotational projection sequences.